Peritoneal dialysis is a therapy of removing or exchanging waste matters or body fluid in a peritoneal capillary vessel of a patient using a dialysis fluid injected into the peritoneal cavity, which is an important therapy for life-sustaining of a renal failure patient. Since the peritoneal dialysis does not always require huge apparatuses or facilities and many assists by doctors and nurses compared to hemodialysis that is another common therapy, it is widely accepted by patients who want rehabilitation or who have difficulty in going to medical care facilities because of their remote locations.
But peritoneal dialysis therapy has some following defects. First, most commercially available DFs contain glucose as an osmo-regulator, which leads to various problems. For example, glucose absorption into the patient body may result in elevated blood-sugar level, lipid metabolism abnormality and insufficient body fluid removal by peritoneal sclerosis. Second, there is another problem associated with the pH adjustment of the DF. Current DFs need to be regulated in an acidic condition to keep glucose stable at autoclaving, but acidifying fluids repetitively injected into the peritoneal cavity is unfavorable for the peritoneal cavity or the peritoneal mesothelial cells.
Third, it is known that 5-hydroxymethylfurfural that is a decomposition product of glucose is formed in a DF containing glucose by autoclaving or longtime storage even when the DF containing glucose is regulated in an acidic condition (q.v. Japanese Patent Kokai No. 71146/1996 for example). So, methods of reducing the formation of the decomposition product of glucose have been studied, for example, a method of removing the decomposition product from a DF and of changing the sterilization method or condition. However, a DF that containing no degradation product of glucose at all cannot be obtained as long as glucose exists in the DF as an osmo-regulator. Fourth, a DF containing glucose has a defect that the body fluid removability become lower with time because of the glucose absorption into the capillary vessel when the fluid is not exchanged for a long time after administered in the peritoneal cavity.
Therefore, methods of using a compound other than glucose as an osmo-regulator are proposed. For example, oligosaccharides, polysaccharides, amino acids, and glucose polymers i.e. starch hydrolyzates are quoted (for example, q.v. Japanese Patent Kokai No. 94598/1998 and Japanese Patent Kokai No. 85701/1996). But these are not yet in practical use because the above osmo-regulators cost a lot, their biosafety for longtime use is not known and they are easily decomposed. Also, methods of using an osmo-regulator containing an amino sugar or L-ascorbic acid is proposed (for example, q.v. Japanese Patent Kokai No. 71273/1999), but these compounds may lead to a problem of storage stability such as decomposition at autoclaving or brown matter production by the reaction with other ingredients. Therefore, development of a DF containing more beneficial osmo-regulator is desired.